S&S Cycle 1250cc Big Bore Conversion Kit - Harley Sportster

Unlock serious power for your Harley Sportster with the S&S Cycle 1250cc Big Bore Conversion Kit. This kit is designed to increase displacement from 883cc or 1200cc, delivering a significant boost in performance without the need for complex machine work or piston rebalancing.

Why riders pick this

• Converts 883cc/1200cc to 1250cc displacement
• Forged pistons with coated skirts for durability
• Includes S&S cylinders and full MLS gasket set
• Eliminates need for machining or rebalancing
• Designed for a direct bolt-on installation

The S&S Cycle 1250cc Conversion Kit offers a straightforward path to increased power for your Sportster. This complete package includes forged 5cc pop-up pistons and S&S 3-9/16" bore cylinders, all designed to work together seamlessly. The result is a substantial bump in displacement and a noticeable improvement in throttle response and overall acceleration, making your Sportster feel more alive on the road.

Engineered for Performance and Simplicity

• Increases 883cc or 1200cc engine displacement to 1250cc
• Forged 5cc pop-up pistons with durable coated skirts
• S&S 3-9/16" bore cylinders for optimal performance
• Complete gasket set (MLS head, base, exhaust) included
• No machining or rebalancing required for installation

A Complete Package for More Power

This kit provides everything you need for a significant engine upgrade, from the cylinders and pistons to the full gasket set. The design eliminates the need for professional machine shop services, allowing for a more accessible performance upgrade. While installation is designed to be straightforward, a proper dyno tune is highly recommended after upgrading to ensure your Sportster's engine runs optimally with the increased displacement.

Specifications

• Brand: S&S Cycle
• Manufacturer Part #: 910-0690
• Displacement Increase: 883cc or 1200cc to 1250cc
• Piston Bore: 3-9/16"
• Weight: 22.15 lb
• Category: Engine Components / Piston Sets

Common questions